1. Field of the Invention
This invention relates primarily to the clamp-like devices known as capotastos or capos which are applied to the neck of stringed instruments, especially guitars, mandolins and banjos, to shorten the effective length of the strings.
2. Description of the Prior Art
In prior art, the capotasto is usually comprised of a bar as a bearing surface with a variety of clamping devices, or straps to hold the capotasto on the instrument. The clamping devices or straps are such that in securing the capotasto to the neck of the instrument, force was applied which tended to move the capotasto ever so slightly in a direction transverse to the strings of the instrument; or the capotasto tended to rotate slightly about the neck of the instrument. This movement or rotation caused small displacement of the strings, and consequently made the instrument out of tune. In addition, some instruments have curved finger boards, and some have flat finger boards, and the capotasto could be repositioned to a different fret satisfactorily only by releasing the clamping device or strap, repositioning, and re-clamping, or re-strapping the capotasto. Hutchins, U.S. Pat. No. 3,933,073 uses a spring clamp. Hutchins, will not provide even pressure across the strings of an instrument whose neck is curved, but will instead rock; and since the pressure is applied to the strings from only one side of the device, the strings will be slightly displaced causing the instrument to be out of tune when attached. Dunlop U.S. Pat. No. 3,598,012, uses a traction strap which will fit almost all sizes of necks. However, the actuation of the toggle lever applies a friction force on the neck of the instrument causing a twisting of the capotasto and consequently de-tuning the instrument. Furthermore, Dunlop cannot easily be moved to another fret without releasing and repositioning the capotasto, and re-actuating the toggle lever. Wowries, U.S. Pat. No. 3,504,589, uses a pulley type system to apply a double force to the traction strap. Wowries, however, will not function on instruments with a curved neck, nor can it be repositioned to a different fret without releasing tension.